more elegant way to conditionally pop

[Be-ing]

I have code like this in two places in my application now:

        while let Ok(AudioEngineToGUIMessage::BufferSizeChanged(_)) = from_audio_rx.peek() {
            if let Ok(AudioEngineToGUIMessage::BufferSizeChanged(frames)) = from_audio_rx.pop() {
                let mut buffer_size_frames = buffer_size_frames.borrow_mut();
                *buffer_size_frames = frames;
            } else {
                unreachable!("AudioEngineToGUIMessage not a BufferSizeChanged message?!")
            }
        }

The while let immediately followed by if let feels verbose and hacky... is there a better way to do this?

[mgeier]

I guess frames is just a number, right? Something that's cheap to copy?
In this case you can probably extract it directly from the peek() call.

Maybe something like this (untested!):

        while let Ok(AudioEngineToGUIMessage::BufferSizeChanged(frames)) = from_audio_rx.peek() {
            let _ = from_audio_rx.pop();
            let mut buffer_size_frames = buffer_size_frames.borrow_mut();
            *buffer_size_frames = frames;
        }

But for move-only types I wouldn't know a better solution.

We could try to add a "conditional pop" function to the API?
Something where you can pass a closure which can decide if the element should be popped or not?
But still we could only pass a reference to the closure, we would still not get ownership.
Or there could be two closures, one for checking and one for getting ownership on success? But this seems a bit convoluted, doesn't it?

[mgeier]

@Be-ing Did you have a chance to try my suggestion? Does it work for you? Or is there anything else to do?